1Corundum Al2O3. Forces were calculated in the 2x2x1 supercell of the hexagonal lattice by VASP with 500eV cutoff energy and 6x6x1 k-point mesh. 2 3Dielectric constant and Born effective charge tensors were calculated with the hexagonal unit cell. 4 5The Wyckoff positions are c and e, respectively, which can be found by 6 7% phonopy -c POSCAR-unitcell --symmetry --pa=auto 8 9The band structure is plotted using seekpath by 10 11% phonopy --nac --band auto -p 12 13seekpath can be installed by "pip install seekpath". 14